Mandarin definitely has many characters with multiple pronunciations. One large class come from literary vs. colloquial reading differences: https://en.wikipedia.org/wiki/Literary_and_colloquial_readin...

Another large class class comes from vestiges of derivational morphology in Old Chinese: https://en.wikipedia.org/wiki/Homograph#In_Chinese For instance, the character 度 in modern Mandarin can be pronounced dù (when used as a noun) or duó (when used as a verb), both of which derived from Old Chinese /daːɡs/ and /daːɡ/, respectively.

With Simplified Chinese characters, some of them come from the merger of originally different words that had similar, but not exactly the same pronunciations. For instance, both 髮 (fà) and 發 (fā) were merged into 发.